Add mentions, pin messages and conversations, and search within chats

apps/api/prisma/schema.prisma

@@ -210,6 +210,8 @@ model Organization {
   conversationSettings   ConversationSettings?
   conversationRooms      ConversationRoom[]
   conversationHiddenMessages ConversationHiddenMessage[]
+  conversationPinnedMessages ConversationPinnedMessage[]
+  conversationRoomUserPins   ConversationRoomUserPin[]
 }
 
 model User {
@@ -2113,3 +2115,32 @@ model ConversationHiddenMessage {
   @@unique([organizationId, externalRoomId, messageId, scope, hiddenByUserId])
   @@index([organizationId, externalRoomId])
 }
+
+/// یک پیام سنجاق‌شده در هر اتاق (برای همه اعضا)
+model ConversationPinnedMessage {
+  id              String       @id @default(cuid())
+  organizationId  String
+  organization    Organization @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  externalRoomId  String
+  messageId       String
+  preview         String       @default("")
+  pinnedByUserId  String
+  createdAt       DateTime     @default(now())
+  updatedAt       DateTime     @updatedAt
+
+  @@unique([organizationId, externalRoomId])
+  @@index([organizationId, externalRoomId])
+}
+
+/// سنجاق گفتگو در لیست — فقط برای همان کاربر
+model ConversationRoomUserPin {
+  id             String       @id @default(cuid())
+  organizationId String
+  organization   Organization @relation(fields: [organizationId], references: [id], onDelete: Cascade)
+  userId         String
+  externalRoomId String
+  createdAt      DateTime     @default(now())
+
+  @@unique([organizationId, userId, externalRoomId])
+  @@index([organizationId, userId])
+}